In general, absorption chillers use LPG, LNC, waste heat, or solar heat as an energy source, and accomplish the cooling effect by operating the absorber, condenser, evaporator and generator to circulate a working fluid of refrigerant/absorbent pair. Contrary to the conventional compression chillers using an energy source of electricity, the absorption chiller which employs heat as an energy source has been regarded as one of the alternative means for overcoming pending problems of the electrical overload during summer season and the regulation of banning the CFC use.
On the other hand, a triple-effect absorption chiller combining medium- and high-temperature generators with the conventional absorption chillers has been developed to maximize the energy consumption efficiency by way of employing refrigerant vapor from high-temperature generator(`GH`) as a heat source for medium-temperature generator(`GM`), and the refrigerant vapor from GM as a heat source for low-temperature generator(`GL`), respectively. The triple-effect absorption chiller is improved in terms of the energy efficiency by about 30%, compared to the conventional double-effect absorption chiller with only one GH.
The triple-effect absorption chiller is, however, proven to be less satisfactory in a sense that inorganic salt-based(e.g. lithium bromide) working fluid to maintain the temperature of GH at 200.degree. C. or more, may bring about a serious corrosion in the chiller and non-condensible vapor formation at a temperature range of over 170.degree. C., eventually decreasing the efficiency of chiller.
In this regard, several kinds of absorption chillers have been suggested in the art, to improve the efficiency of conventional absorption chillers and the corrosion problems of triple-effect absorption chillers.
For example, U.S. Pat. Nos. 4,520,634 and 5,205,136 and Grossman et al.(see: Grossman, G. et al., ASHRAE Trans., 100(1): 452-462, 1994) describe multiple-effect absorption chillers whose efficiency is highly improved, while remaining the corrosion problems caused by working fluid operating at a high temperature.
Further, U.S. Pat. No. 4,732,008 teaches a triple-effect effect absorption chiller employing two refrigerating circuits to overcome the said corrosion problems, and Ouimette et al employs one additional high-temperature circuit of less corrosible working fluid to the conventional double-effect absorption chiller(see: Ouimette, M. S. and Herold, K. E., Proc. International Absorption Heat Pump Conference AES vol. 31, American Society of Mechanical Engineers, pp233-241, 1993).
U.S. Pat. No. 4,171,619 and Sawada et al.(see: Sawada, N. et al., Proc. International Absorption Heat Pump Conference AES vol. 31, American Society of Mechanical Engineers, pp471-476, 1993) illustrate a variety of methods for applying compressors to improve the efficiency of single-effect absorption chiller. In addition, Boer et al disclose a double-effect absorption chiller with one compressor employing a working fluid of methanol-glycerol to improve the efficiency of the chiller(see: Boer, D. et al., Proc. International Absorption Heat Pump Conference AES vol. 31, American Society of Mechanical Engineers, pp483-486, 1993).